Supercharger control apparatus



Ju1y16,1946. A. c. STALEY 2,404,323

SUPERGHARGER CONTROL AIPARATUS Filed Jan. l, 1942 Patented July 16,1946

SUPERCHARGER CONTROL APPARATUS Allen C. Staley, Birmingham, Mich., assigner to Chrysler Corporation, Highland Park, Mich., a

corporationo'f Delaware Application January 1, 1942,*Serial No. 425,298

" 12Claims.v (Cl. 12S-119) This invention relates to an improved control i apparatus for superchargers and associated, fuel system for internal combustion engines. Y

More specically, the invention pertains to an improved control apparatus of this kind which is particularly adapted for superchargers of aircraft engines. Y

It is Well known that axial flow as well as other superchargers stall when the relation of the density and volume of the air entering the inlet of the supercharger to the discharge pressure l ,is not maintained within predetermined limits.

The limiting discharge pressure, above which aero-dynamic `stalling willv occur, decreases in value as the inlet air density decreases.. For each xed speed of operation of a given supercharger, the limiting ,discharge pressure follows a1 curve, during variation of inlet air density, which can be determined experimentally and which is known as the pumping limit curve of the supercharger,

Since, in the operation of an aircraft having an engine provided with a supercharger, changes in inlet air density occur with changes in altitude 'and temperature, discharge pressure-altif tude pumping limiting curves, such as those inlet air densities such as result from variations in the altitude and temperatures at which it is operated. Y

A further object of the invention is to provide at the discharge end of a superchar-ger of this kind, a spill valve which tends to open under the discharge pressure for'variably limiting the latter by reducing the pressure and increasing the volume of the air handled at diverseV speeds, and inlet air densities such as result from changes in altitude at which operation occurs. l

A still further object of the invention is to p'rovide mechanism which isresponsive to both inlet air density and operative speed of the super,- charger for so automatically variablyopposing opening of the pumping limit control spillvalve as to maintain the discharge pressure, throughout a wide range of speeds and inlet airdensities, below different predetermined values correspondingto the speed andinlet` air density abovewhich stalling of the supercharger would'. occur.

Other objects of the invention are to provide an air compressing unit for creating the variable force required to oppose opening of the spill valve under diverseoperating conditions which is subjected to substantially the same inlet air density as the supercharger and which is operated at a speed directly proportional thereto and to provide an air compressing unit for thispurpose having characteristics such thatthevariation of the speed at which it is driven andi the variation of the density of the air at its inlet produce such changes in the force developedq thereby and opposing opening of the spill valve as vto limit the discharge pressure of the supercharger to a value vbelow that at which the latter would stall at each speed of operation and in that air density respectively within relatively wide ranges of speeds and air inlet densities andwithout holding the vsupercharger discharge pressure at unnecessarily low value at any speed or inlet air density withi Vsaid ranges. e

ywith which the latter is associated can be throt- -tled; to provide a manually operable spill valve and a manually operable throttle valve in control means of this kind for reducing the supply of air from the supercharger tothe engine by ex- `hausting a portion of such air and by obstructing the air flow to the engine respectively; to provide a control system for the above mentioned valves which is interconnected with each thereof and adapted to sequentially operate the valves in a vpredetermined order; andto Vprovide a I control system of this kind which, in reducing the supply of air to the engine from amaximum value, iniy tially opens the manually, operable spill valve and i Still furtherobjects of the invention are to provide mechanism in the outlet of `a supercharger for controllingthe. fuel weight regulating means -of a liquid fuel injectionlpu'mpinresponseto the weight of air supplied by, asuperchargerto an engine; and to Vprovide mechanism of this kind which-is so located with .respect to the outlet ,of the supercharger as to be responsive to .only

that portion of the air operated upon by the Ysuper- Vcharger which is actually/supplied'to the engine.

An illustrative embodiment of theinvention is shown in the accompanying drawing. in which:

Fig. l is anjend elevational viewof (an internal V ing limit curves of Y of the supercharger taken on the line v2-'12 of Fig. 1.

Fig.v 3 is a transverse sectional view of one ofk the blades of the rotor of the supercharger taken on the line' 3,-173Lof Fig. 2.

Fig. 4 is asectiona'l view of one' ofthestation'-V ary bladesV taken on the line 4-4 of Fig. A2.

Fig. 5 discloses typical pressure altitude pump'- a supercharg'er of tha-axial"V owrtype. Y I A Fig. 6is a sectional view taken on the line 3.S ofV Fig. 2.

Fig. 7 is an enlarged sectional View of valve and control therefor.

charge of the pump isY 4 variably regulated. Fuel discharged from the pump 22 is supplied to the y engine by a conduit 33 which may be connected In the form of the invention illustrated in the? I drawing, theimprovedfsupercharger control apparatus embodying the-invention is illustrated. as applied to a supercharger,generally designated `bythe numeral I0, of the axial flow type which is illustrated in connection with an internal combustion engine generally designated bythe nu- -meral II suitable `for propelling aircraft and of the type which has a -fuel system injecting fuel into the engine manifold or theengine cylinders.

The supercharger I9 comprises a YVcasing 1I2 having an air inlet I3 at one e'nd and a discharge chamberand air outlet I4 and I5 respectively at itsl opposite end.y Extending centrally through the casing I2gis a shaft VIgI'journalled in suitable bearings Il and I 8` and on which are xed a series of air propelling elements I9eachV provided with fan blades 29. The fan blades 29 of successive air propelling units I9 are of such shape and pitch as to progressivelyincrease the pressure of the rair passing from the inlet I3 to the discharge chamber I4 in successive steps. Fixed blades- 2I carried by the casing I2 "arelr disposed between blades of successive air propelling units I9 in order to properly direct the air propelled by the blades of/one unit for `further propulsion of the next'successive unit. -V i Air under pressure delivered by the final air propelling unit I9 Vis received in the discharge chamber I4 from which it flows through the'oulet I5 to the manifold of the engine II. i

The weight of liquid :fuel supplied to the engine isproportioned with respect to the weight of air fed thereto from the vsupercharger by suitably t controlling the discharge of liquid fuel from a variable liquid fuel pump of conventional construction, generally designated by the numeral 22. The control vapparatusby which this is accomplished comprises'a bellows 23 contained in a casing 24, the interior of which is connected by a pipe 25 with the interior of the discharge chamv ber I4 so as to maintain pressure inthe casing 24-`proportional to the air pressure in the discharge chamber I4- The interior of the bellows 23 is connected by `a pipe 25 with the Venturi tube 21 disposed centrally of the passage through the discharge chamber I4 in order to subject the interior of the bellows to. pressure changes in proportion to changes in velocity of air ow through theidischarge chamber and to the engine.YAY The Venturitube is so located'as to be responsiveonly to that portion of the air operatedjupon byithe lsupercharger which is actually fed to `the engine.`

Theibellows 23is mechanically connected with a stem" za attached to the bellows 2a and to a bellcranl`29 which is in turn connected with' a 'control rodt'e by which the quantity'f Yfuer dis-ii to an injection nozzle (not shown) arranged to discharge fuel directly into the cylinder heads 15 or into the intake manifold It of the engine.

, Since the pressure applied in regulating theY pumpn22rthrough the bellows 23 is a function of the'I square ofA the air velocity inthe discharge passage" I4, there isa tendency to increase the opposite end. The interior of the chamber l'I is line leading to the inlet side of the pump 22, The interior of the bellows 'i6' is connected by a conduit VSI with a venturi 82'arranged concentrically of the fuel line 83. The .venturi 82 subjects the interior 'of the 'bellows to changesv of pressure in proportionto the'fuel low through the conduit 8i). The bellows 13 thus acts to reduce the fuel increasing action produced by the bellows 23 as to prevent the fuel-air ratio from excessively increasing Ywith increased air iiow.

This control mechanism is therefore Apredetermined to maintain a fuel-air ratio as demanded by engine requirements 'under' a wide Irange of operating conditions. l l

Privide at the inlet end of the discharge chamber'I`4 is an exhaust'outlet 3l 'leading to the interior of a casing 32 `and having'an opening 33 communicating with atmosphere. The wall of the casing 32has a valve seatv against 'which fa va1ve'34 bears. The valve 34 is normally held in closedposition by a bellows 35 to the interior or' which air under pressure is supplied through a conduit 39. The air-supplied'vthrough the con-v duit 36 is impelledlbyY a pilot blower generally designated by the'nu'meral31ywhich includes a casing 38, an inlet 38a, and rotor 39. Therotor 39 is driven in timed relation to operation ofthe superchargerfwhichf'm'ay bel' 'driven in timedV re`- lation to the crankshaft'ofthe engine Il.y The supercharger lalso may be driven in 'any vmanner from any suitable power sourcebutfor l`p`urposes of illustration the drawing shows ai drivevfojr the supercharger comprising meshedfV bevelled :gears 49' and 4I on the supercharger shaft I andon an intermediate driving shaft 42 respectively The intermediate shaft 42^is drivingly Vconnected. with the crankshaft 43 of' the engine by bevelled gears 44 arid 45. VV Mounted; on the shaftn I6 of the sup'erchargerY is a worm 45 which is meshed with a worm gear 41 on vthelower end of a shaft48. The upper end of; the shaft 48Afis drivingly connected to the rotor 39 of theA pilot lair compressor by'suitable Ygearing 49,u

priseanvaxial flow or centriiugaltype'blower, the

output ofwhichis predetermined lby 'tsfconjstruction to sdvariabl'y"opposopeningof tha-pumpiing limit spill valve 34 as to prevent the discharge pressure of the'supercharger I0 from exceeding that value at which aero-dynamic stalling occurs throughout relatively widecorrelated ranges of operating speeds and inlet air densities. This is accomplishedwithout unnecessarily limiting the discharge pressure vfar below its pumping limit during any operating conditions. l

The inlet end of the discharge chamber I4 is provided with a second exhaust passa-ge 50 in which is disposed a valve 5I for variably obstructing vthe escapement of air from the pressure chamber I4. The outlet I5 of the discharge chamber I4 islprovided with a throttle valve 52. The valves 5I and 52 may be manually regulated for changing the supply of air to the engine by a common actuating rod 53 which is shiftably mounted in supporting structure (not shown). The, valves 5I and 52 are operatively connected by operating levers 54 and 55 respectively with the control rod 53 in suchv manner that when the throttle valve 52 is 'fully ppened as illustrated in Fig. 2, the escapem'entfvalve 5I is'fully' closed. This is accomplishedby providing on the rod 53 a collar 56 and a shiftable abutment 51 between which is disposed a coil spring 58.' The coil spring 58 urges the shiftable abutment 51 against the operating lever 55 of the valve 52 when the control rod 53 is in the position'shown in Fig. 2 thereby holding the lever 55 against a stop 59 and retaining the throttle valve 52 in open position. The escapement valve 5I is similarly held in closed position under the `vabove conditions by a shiftable abutment 60 which is urged leftwardly as viewedin Fig. 2 by a coi1` spring 6I bearing against the collar 62 on the rod 53. Provided on the rod 53 is a xed abutment 64 which is spaced rightwardly, as viewed in Fig. 2, from the shiftable abutment 51 in order to allow lost motion action between the control lever 55 and the rod 53 during leftward movement of the latter as viewed in Fig. 2.- A similar abutment 65 is provided on the rod in spaced relation to the shiftable abutment 60 in order to allow lost motion action between the rod 53 and the operating lever 54 of the escapement valve 5I when the rod 53 is shifted rightwardly as viewed in Fig. 2.

In the foregoing control apparatus, when the maximum supply of air is beingA fed to the en@y gine, the escapement valve4 5I is closed and the throttle valve 52 is fully opened asl illustrated in the drawing. In this positionthe spring 58 is open valve 52. l.Further movement of. rod53 to the left causes further movementto the 'leftwof abutment 64, and. since this abutment'` is nowin l engagement with lever 55, `counterfclockwise movement of the;lever.55 and valve 5.2 takes place with the valve 52 reaching closed position. A stop, not shown, prevents movement of the valve 5I beyond open position. The abutment65 `moves tothe left away from the lever 54. Theabutment 62 also moves to the left,.but this is possible because the spring 5I can be and. is.` compressed.

The rod 53 has now reached an extreme left position, in which the valve 52 is closed, and the valve 5I is open. Thus the supply of air to the engine is further reduced, not only because the valve 5I is open, but also because the valve 52 now obstructs passage of air to the engine.

In order to prevent the discharge air pressure from exceeding a selected value under any Voperating conditions, a safety valve SI5V is provided in an opening 61 formed in the wall fofthel exhaust passage 50. TheAvalve 66 is normally held y'in closed position by a spring (iB-.and is adapted taining operation of said supercharger within its pumping limit throughout relatively wide ranges of operating speeds and inlet air densities respectively including a spill valve for discharging air to atmosphere subjected on one side to and compressed, and the abutment 64 is spaced ri'ghti wardlyof the' lever 55. The control rod 5 3isin an extreme right position. Movement fof the rod 53 to the left causes the collar; 6:2 to be moved to the left, the collar 62 acting through the spring 6I to move the abutment` B0 tothe left. f This causes the lever 54 to be rotated counter-clockwise, and the valve 5I to be moved to openposi# tion. The abutment G5 also moves to the left with the rod 53,' thereby permitting the above to happen. In the meantime the abutment 64v has been moving to the left and has flnally reached the lever but has not moved the lever 55 counter-clockwise so as to disturb the open position of the valve 52. The collar 5E has also moved'to the left, but the spring 58, because of its expansion from a compressed state, maintains the abutment 51 in engagement with the lever 55, thereby maintaining the open condition of the valve 52. Thus the rod 53y is in an intermediate position, and both valve y 5I and valve 52 areA open. Opening ofthevalve 5I decreases the o'w of lair to'the 'engine past the adapted to be opened by the discharge pressure of said superchargenand means responsive to changes in both the speed of operation of said supercharger and the air density in the vicinity of its air inlet for variably urging said valve toward its closedA position with a force varying directly in accordance with speed'and directly with respect to inlet air density.

2. In a supercharger for supplying airV to' an internal combustion engine; apparatus for maintaining operation of said supercharger within its pumping limit throughout relatively wide ranges of operating speeds and inlet air densities respectively including a' spill valve subjected on one side to and adapted to be opened Aby the discharge pressure of'said supercharger, and'means responsiveto changes in both the speed of operation of said supercharger and its inlet air density forr variably urging said valve toward its closed position with a force varying in accordance with speed and inlet air density,` said means including anair pressure responsive element operating on the other side of said valve, a pilot air compressor having an air inlet subjected to substantially the same air density as the air inlet of said supercharger and having a discharge outlet connected with said element and mechanism for driving said pilot air compressor in timed relaf tionship with respect to said supercharger.

gnomes percharger` .includingQa spill valve sulaiected` on one sidel toand adapted to be opened yby the dis"- charge pressure" of. said 'superc-zh'arger,` means re.

Y sponsive to. both the speed. of operation. ofsaid su1; erchargerV andv .its vinlet air density. lfor Vari- V,ablyopposing'opening of -said spill valve includ'- oneside to andadapted'tobe.opened by, the dis-v v charg; pressure of said supercharger', meansree 'sponsii/eV toiboth the speedf'of operation of said superchargerand its inlet air dens-ity for Varivablyxopposing opening of said` spill valve including a pilot air compressorfdrivenin timed relation to' sai'clrsupercharger andanair cl'iamberA connected /Withjthe discharge thereof;V for applying ava-ive Vclosingforce on the opposite Y'side ofjsaid spill Vvalve, said'air compressor being so constructed and drivingly connected lwith saldi supercharg r as to operate well Withinfits pumping limit throughout the operating rangejiof said super-- charger andk throughout the variations of the inlet air density towhich it is subjected'in normal operation.V Y Y Y 5. In a supercharger for supplying air to an Vinternal combustion engine of an aircraft; ap-

paratus for maintaining the discharged pressure of said supercharger Within the limits of a definite predetermined pumping limit curve during operation at a substantially Wide range of altitudes including a Valve for' exhausting air from the discharge side of said supercharger adapted to be opened by discharge pressure,v and mechanism for urging said valve toward closed position with .force oit-variable magnitude, said mechanismbeingfso constructed and, arrangedas to lvary said force inversely With respect to variations in altitude and directly with respect tovariationsin speed ofy operation of said compressor.-

V6. lnasupercharger having a dischargechamuerpgovided wit-ha main outlet forgsupplgying air to an' internal combustionA engine and an escape.- ment outlet for discharging air r-tovatmosphere", mechanism for controlling the Lsupplyi air; to saidl engine including avait/ein saidmain outlet,

a valve in said escapementoutlet,k and control apparatus-.foropening and closing said valves in predetermined sequence,- fsaidfcontrol apparatus being so constructedand arranged as; toY initially positively open said--escapement valve and sub? sequently close said mainval'ige during reduction ot the supply of air to said engine froma-.maxi

mum-toga minimum value andtoj, initiallyopen said. main valve andsubsequently positively close saidlescapement Valve during increasing of the supply'ot air to said engine ironia minimumV toa maximum Value.

'7. In a supercharger having a discharge chamber providedwith a'main outlet. forgsupplying air toy an internal combustion engine and an escapenient outlet, mechanism Lfor* controlling the supply of A`air to said engine `including -af valve ineaidime-in Outlet@ @Wein-.Said ,escapement 58 tuating said', valves and means voperativ'ely. cornnecting. saidA rod 'with said mainioutlet 'and escap'ement Valves respectivelyinchiding fa .valve operating lever' associated with each. ValveV and spaced yield'able and; xed elements on opposite sidesv of' each of' "said- Lievens "r'espctively lsaid yieldable 'abutments being adjacent each other and adapted toacconmodatemovement of each leve'r by? itsV associated Xed abutment While theotherlever remains at rest during movement of saidl rodf in respectively-'opposite -directions throughout; a predetermined portion of-` its range ofmove'ment.

8.- The method of maintaining operation-'of a supercharger for aninternall combustion en"-v gine` within its pumpingl limitV which consists in variablyfd-ischarging air to atmosphere` from the dischargefcharnber ofv saidsupercha-rger, andA varlably opposing such discharge of airl autolrlati` cally in accordance with variationsinA the Vinlet air; density andspeed of operation of said supercharger bythe force of asourceoi airpressure Varyingv in pressurefdirectly with respectto Variations in 'speed of operation ofV 'said supercharger and inversely withrespectfto variations in the altitudejat which it is operated;

9. AA fuel and, air charging systeml -for an-internal combustion engine comprisinga variable liquid fuel pump having a control'memberffor predetermining the Weight: cfjA fuelv ldisclfrarged therefrom, an axial flow superchargerhaiing an air inlet -andj ai compressed air outlet communi'- cati-ng with said engine andfrincluding pressure and ypumpinglimit control mechanism hai/ing air spilling outlets spaced onthe up stream s ide of said compressed air outlet, and apparatus for ac.- tuating said fuel Ypump -control4 member including; an element responsive to anyV condition-1 and located in the air stream propellediby' said supercharger between said airfspill'ingg outletsandsaid compressedI air outlets, said element being subjected-to the/action ofi-only that portion of the air operated uponlby said supercharger which is discharged from vsaid .compressed air outlet.

-10. Afueland air charging systenfr nintern'al combustion eginecl'ris'ig a Variable liquidfuel pump having vavcntrol iiemberfor preclet'erininig the weight.v of fuel. discharged therefrom, an axial flow ,supercharger ha'iing van air inlet and comprssdir itl''t. 'ilicatihgwthesaid engine, mechanism fr onflungtnesuppIy of air, from' said-Compressed'au Outlet Comprising a Variab1. throttle Valv'i Said outlet and a variable air spillingputlet spaced ,on the up stream side from said'compresseu air-'outcortrolmmbver including an elementrresp'orsile to air conditions and located, between said. air spllillgY Outlet ldsad Compressed ai? Outlet, said/element being'subjettedto the actonof that portion onlyA of thel air. operated nlip'ri by said superchargerwhich is discharged from' said coinpre'ssed all", Outlet.

1l.,k A fuel and airv chargingsystem for aninternalco'mbustion engine comprising a Variable liquidI fuel .SupplyV system having ,a control member for predetermining the weight of `fuel discharged therefrom, a /superchar'geii having' an airmiet and ai compressed air, outlet communieating with said engine,`r mechanism for' controlling the supplyv of. air'ffrorn, said compressed air outlet comprising. aV variable.. throttle. valvein said outlet f and an: air .spilling outlet ,spaced on the upstream sidefrom-vsaid compressedair outlet; andapparatus ffonactuatinggsaid -fuelfsysteni control member including an element responsive to air conditions at a location between said air spilling outlet and said compressed air outlet, said element being subjected to the action of that portion only of the air operated upon by` said supercharger which traverses said location.

12. The method of maintaining operation of a supercharger for an internal combustion engine 10 within its pumpmg limit Which consists in variably discharging air to the atmosphere from the discharge chamber of said supercharger, and Variably opposing such discharge of air-*automatically and directly with variations in the inlet air density and directly with variations in speed of operation of said supercharger.

- ALLEN C. STALEY. 

